Modified shuss knitted netting

ABSTRACT

A knitted netting includes longitudinal polyolefin ribbons and lateral polyolefin ribbons knitted with the longitudinal polyolefin ribbons to form knitted netting. The lateral polyolefin ribbons of the knitted netting have an actual shuss length more than 110% of a calculated shuss length for the knitted netting. The actual shuss length being in excess of 110% of the calculated shuss length for the knitted netting prevents transverse shrinkage of the netting.

This is a divisional of co-pending application Ser. No. 09/641,949,filed Aug. 21, 2000, which is continuation of Ser. No. 08/978,235 filedNov. 25, 1997 now abandoned.

BACKGROUND OF THE INVENTION

The invention relates to knitted netting, and more particularly, toknitted netting as is used in wrapping, e.g., loads on pallets and balesof agricultural products. More particularly, the invention relates toknitted netting used in wrapping wherein the knitted netting is designedto minimize the transverse shrinkage of the netting.

In 1 FIG. 1, Raschel knitted netting 10, including shuss (schuss), or“lateral” ribbons 12, and franze (longitudinal) ribbons 14, also knownas franse ribbons, is shown and further described in U.S. Pat. No.5,104,714 to Lieber et al. Because of the triangular pattern in theknitted netting, all Raschel netting becomes narrower when pulledlengthwise. For example, when wrapping a pallet with conventionalRaschel netting, when the netting is stretched about 60%, the nettingmay change in width from 50 cm to about 25 cm. When a longitudinal forceis applied to the knitted netting, the franzes become longer. The longerthe franze gets, the longer the shuss must be to maintain the samenetting dimensions. However, up to a certain degree of elongation, theshuss does not extend because the shuss tends to straighten rather thanelongate. The straighter the shusses, the smaller the distance betweenfranzes, and the narrower the netting becomes resulting in transverseshrinkage of the knitted netting.

Transverse shrinkage has been inherent in Raschel knitted netting for aslong as machines to produce such knitted netting have existed. It iswell known that conventional Raschel netting becomes narrower even whilebeing knitted on Raschel knitting machines. For example, if 48″ Raschelknitted netting is desired, about 50″ netting is knitted because thenetting becomes narrower by about 2″ between the knitting and thewinding zones.

When a constant netting width is needed, the width can be regulated bychanging the shuss tension in the knitting machine. The producers ofknitted netting machines provide a facility on their machines toregulate the netting width, which depends on many factors including thetype of material, temperature, ribbon dimensions, knitting tension, andknitting pattern. The knitting machine producers are aware that nettingshrinkage is inherent in Raschel knitted netting. Such producers arealso aware that increased tension on the shuss creates a narrowernetting and loosened tension on the shuss prevents narrowing to somedegree. Changing the shuss tension, however, is insufficient to fullyovercome transverse shrinkage in knitted netting.

In the prior art is U.S. Pat. No. 4,781,291 to Van Ginhoven which isdirected to an extruded netting. Van Ginhoven recognizes that a problemin Raschel knitted netting “is that it shrinks in overall width whenpulled lengthwise”. (Col. 1, line 19.) Thus, Van Ginhoven appreciatesthat Raschel knitted netting shrinks when pulled lengthwise due to thegeometric pattern of the knitted netting. Van Ginhoven addresses thisproblem by proposing a netting of square openings, instead of Rascheltriangles, to solve the problem. By having transverse strandsperpendicular to the longitudinal strands, creating rectangular openingsinstead of triangular, transverse shrinkage is overcome.

Accordingly, there is a need in the art for a knitted netting which doesnot shrink at all during the production process. Further, there is aneed in the art for a knitted netting that maintains its full widthduring production and may also be widened to more than its fullproduction width.

SUMMARY OF THE INVENTION

With the foregoing in mind, the Modified Shuss Knitted Netting inaccordance with the invention provides a “modified” shuss relative tothe shuss of conventional knitted netting. A modified shuss is a shusswhose length is as long as is desired, which is in excess of anddistinct from conventional knitted netting with shuss loosened only tothe maximum permitted by the knitting machine. The netting according tothe present invention may have at least one modified shuss 18, mayinclude modified shusses 18 located along the outside edges of thenetting, or all of the shusses of the netting may be of the modifieddesign. Each modified shuss may be formed a plurality of ribbons or froma single ribbon.

In accordance with the invention, a knitted netting includeslongitudinal polyolefin ribbons (also known as franse ribbons) andlateral polyolefin ribbons (also known as schuss ribbons) knitted withthe longitudinal polyolefin ribbons to form knitted netting. The lateralpolyolefin ribbons of the knitted netting have an actual shuss lengthmore than 110% of a calculated shuss length for the knitted netting.

In accordance with a further aspect of the invention, a wrapped bale ofagricultural crops includes a cylindrical bale of agricultural crops anda knitted netting having longitudinal polyolefin ribbons and lateralpolyolefin ribbons knitted with the longitudinal polyolefin ribbons toform knitted netting. The lateral polyolefin ribbons of the knittednetting have an actual shuss length more than 110% of a calculated shusslength for the knitted netting. The knitted netting may also extendabout the circumference and over the edge of the cylindrical bodyenclosing and maintaining the crops therein.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, referred to herein and constituting a parthereof, illustrate preferred embodiments of the invention and, togetherwith the description, serve to explain the principles of the invention,wherein:

FIG. 1 shows a conventional knitted Raschel netting;

FIG. 2 shows a knitted Raschel netting in accordance with the invention;

FIG. 3 a illustrates a roll of knitted netting;

FIG. 3 b illustrates a partially unrolled roll of knitted netting;

FIG. 3 c illustrates calculation of shuss length for knitted netting;

FIG. 4 a shows a corrugated trick plate for use in a knitting machine;

FIG. 4 b shows a single round piece for use with a corrugated trickplate;

FIG. 5 shows a shrinkage/elongation curve for conventional knittednetting;

FIG. 6 shows a shrinkage/elongation curve for knitted netting accordingto the invention;

FIG. 7 shows a hay bale wrapped with conventional knitted netting; and

FIG. 8 shows a hay bale wrapped with knitted netting according to theinvention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 2 shows a knitted Raschel netting 16 in accordance with theinvention which provides a “modified” shuss 18 relative to the shuss ofconventional knitted netting. The modified shuss has a length longerthan the shuss length obtained when loosened to the maximum permitted bythe knitting machine. For example, a knitted netting including amodified shuss that is about 30% longer than the prior art shussprovided by the knitting machine becomes narrower by about 12% at 60%elongation of the knitted netting during wrapping, while the samenetting without modified shuss becomes narrower by about 50% at 60%elongation.

The shuss is created by moving the shuss ribbon between two needleswhile the netting being knitted moves longitudinally in the knittingmachine. Because of the two directional movement, the shuss 18 createslegs of a triangle while the franze 20 creates a triangle base. Thetension of the shuss can be adjusted, but is limited and can onlyproduce shuss with an actual length less than 110% of the calculatedlength of the leg of the triangle created by moving the shuss ribbonbetween two needles at the longitudinal speed.

The preferred amount of elongation of the shuss length depends upon theparticular netting application. For elastic pallet wrapping, thepreferred actual shuss length is about 135% of the calculated shusslength for the netting. For conventional wrapping netting with anelongation at break of about 20%, a modified shuss is not needed becausesuch netting only elongates about 1-3% in normal use and does notexhibit transverse shrinkage.

The characteristics of the Modified Shuss Knitted Netting according tothe invention may be seen by comparing an actual shuss length of a givennetting length more than 110% of the calculated shuss length. TheModified Shuss Knitted Netting exhibits reduced lateral shrinkagerelative to netting produced with an actual ribbon length equal to thecalculated ribbon length upon elongation of up to 100%. The suggestedprocedure for comparing actual shuss length with calculated shuss lengthis illustrated in FIGS. 3 a through 3 c and may be described as follows:

(1) Measure the length (L) between the two extreme franzes on a roll ofknitted netting as shown in FIG. 3 a. (The overall roll length is shownas O.)

(2) Divide the length (L) by the number of franzes minus one to definean average distance between two franzes (H).

(3) Define an average length (A), i.e., the base, between two trianglelegs each having a length (S/2), by unrolling some of the knittednetting, measuring the total length often such “bases” and dividing thattotal length by 10 to define the average length. (A) as shown in FIG. 3b. This measurement should be performed while applying about 50 g to thefranzes on which the shuss will be measured.

(4) Calculate the shuss (S) length between two triangle legs as shown inFIG. 3 c as follows:$S = {2\quad\sqrt{\left( {A/2} \right)^{2} + H^{2}}}$

(5) Determine an actual shuss length for distance 10A by unrolling someof the knitted netting and transversely cutting the franzes and shusses.Take out the shuss between two franzes and measure the length of theshuss while flattening the shuss on a flat plate to determine the actualshuss length (ASL).

(6) For Modified Shuss Knitted Netting, ASL will exceed 10S by more than10%.

In summary the calculation may be described as${100 \times \frac{{measured}\quad{shuss}\quad{length}}{{calculated}\quad{shuss}\quad{length}}} = {\%\quad{{modification}.}}$

Therefore the modified, i.e., actual, lateral/shuss ribbon length may bedefined as being at least 10% greater in length th the calculatedlateral/shuss ribbon length, which is synonymous with the definition, amodified or actual lateral/shuss length that is 110% of a calculatedlateral/shuss length.

Existing Raschel knitting machines do not provide a facility forproviding modified shuss. The maximum loosened shuss which can beknitted on these machines can at best widen the netting a little bit,but even so the netting will tend to narrow.

In order to create the modified shuss according to the invention and toovercome such knitting machine limitations, a corrugated trick plate asshown in FIG. 4 a may be incorporated into the knitting machine. The useof a conventional trick plate is illustrated, for example, in U.S. Pat.No. 3,646,782 to Kohl. The corrugated trick plate includes a flat plate22 providing corrugations 24 which force the shusses to traverse alonger distance as the shusses move between the knitting machine needlesthan would be traversed in a conventional knitting machine. The shussescannot move in a straight line; the shusses must follow the curvature ofthe corrugated trick plate. Accordingly, when the knitted netting leavesthe corrugated trick plate, the shuss length is longer than theoriginal. The thicker the corrugations between needles on the flatplate, the longer the shusses that are produced.

Where an equal amount of shuss modification is needed over the completenetting width, a corrugated plate as described with respect to FIG. 4 amay be used. Where modified shuss is required only on particularshusses, a flat plate absent corrugations (not shown) may be used toproduce a thicker area between particular needles. This can be achievedby attaching a round piece 26 to the flat plate by means of a screw orother suitable fastener. Round piece 26 is shown in FIG. 4 b.

With the Modified Shuss Knitted Netting it is not possible to regulatethe netting width by increasing the shuss tension as was done inconventional knitted netting. When knitting with modified shuss, thewidth will always remain the same and will be a function of the numberof needles and the distance between them. There will be no shrinkingduring the knitting process. The width in the Modified Shuss KnittedNetting can differ only in quantum amounts equivalent to the distancebetween needles.

It may be appreciated that there are many distinct advantages to theinstant invention. Insertion or removal of a single round piece issimple. Locating the right parts in the right place when differentamounts of shuss modification are needed at different places across thenetting is simplified, as a different thickness of the single roundpiece can be used. It is important that when the same amount of shussmodification is needed over the netting width, a single corrugated trickplate (as shown in FIG. 4 a) may be used.

The amount of shuss modification created on the complete netting widthcan be varied to some degree by regulating the shuss tension. This isdone by regulating the shuss tension on the existing machine. Only whena different amount of modified shuss across the netting width is neededwould different single round pieces (distinguishable by their differentthicknesses) be used.

It may be appreciated by those skilled in the art that the ModifiedShuss Knitted Netting according to the invention provides manyunexpected advantages over conventional knitted netting. In particular,the Modified Shuss Knitted Netting is somewhat stronger, perhaps becausethe shusses don't create radial stresses on the franzes as inconventional knitted netting. Comparing FIGS. 5 and 6, it may beappreciated that the slope of the shrinkage/elongation curve created bythe Modified Shuss Knitted Netting is a function of the amount by whichthe shuss is modified. A very small degree of shrinkage always occurs inthe Modified Shuss Knitted Netting at the moment when longitudinal forceis applied.

The shrinkage-elongation curve for modified shuss netting prepared inaccordance with the present invention is depicted in FIG. 6. By notingthe grid projected by the % Shrinkage and % Elongation indicia on thex-y axes of FIG. 6, it can be readily seen that for the modified shussnetting produced in accordance with the present invention at elongationof between about 10% and about 20%, the modified shuss netting exhibitsshrinkage of greater than 0% and up to about 10%; at elongation ofbetween about 20% and about 50% the modified shuss netting in accordancewith the present invention exhibits shrinkage of between more than 0%and up to about 10%; at elongation of between about 50% and about 80%,the modified shuss netting in accordance with this invention exhibits ashrinkage of between about 10% and about 30%; at elongation of betweenabout 80% and about 100% the modified shuss netting in accordance withthe present invention exhibits a shrinkage of between about 20% andabout 50%.

Comparing FIGS. 7 and 8, when wrapping a round hay bale by usingModified Shuss Knitted Netting wider than the bale, a considerableamount of over-edge coverage is achieved considering the number offranzes on the outside of the hay bale. (Note that in the figures D1=D2,L1=L2, and D3>D2.) Over-edge-wrapping of hay bales provides theadvantage of increasing the covered area on both sides of the bale.Because the franze length would be reduced on the smaller diameter atthe extremities, some folding or pleating would be expected to occur asthe net spread over the edge. However, the amount of over edge coveragehas been found to be a function of the net elongation while wrapping andthe amount of modified shuss. For example, if the circumference lengthof the last franze is x % shorter and the bale wrapping is performedwith an x+1% stretch, then the last franze will create a 1% elongation.In this case, even if the shorter franze stretches only 1%, the shussesspread to their maximum length with respect to the length of themodified shuss. Therefore, the distance between the two franzes in thiscase is larger than the distance between the two needles on the machine.The netting merely does not shrink in width when wrapped around the bale(the distances between franzes remain nearly constant withoutnarrowing), but on both sides of the bale, the distance between franzesbecomes more than the distance between needles, due to radial forcesthat are created which spread the shusses to their maximum modifiedlength. It may be noted that in U.S. Pat. No. 4,917,008 to van denWildenberg, the over-edge coverage is accomplished using elasticelements on both opposite longitudinal edges. Such elastic elementsaren't needed when using the instant invention, due to the new nettingproperties.

In addition to the foregoing properties, the new netting can also bewidened to more than its original width, even where longitudinal forceis applied on the netting. Such phenomenon is created on the peripheralportions of the bale as discussed above.

While the invention has been described in its preferred embodiments, itis to be understood that the words which have been used are words ofdescription, rather than limitation, and that changes may be made withinthe purview of the appended claims without departing from the true scopeand spirit of the invention in its broader aspects.

For example, the new invention is applicable to all kinds of nettingcontaining longitudinal franze and lateral shusses. Even in netting withhorizontal shusses which create quadrant openings there will be anadvantage if it is knitted with modified shuss. Such netting usuallydoesn't shrink on its lengthwise direction; but without modified shussit couldn't be widened to more than its original width. Further, theinstant invention is not limited to any particular material or kind ofstrands, tapes, monofilament, multifilament, or the like. Still further,it may be appreciated that a knitted netting may be produced with onlysome loosened shusses on both sides or at any place along the net width,the netting can be widened during wrapping process, at any predeterminedarea of the wrapped load, etc.

Knitted netting may also be produced with different amounts of shussmodification. If a given number of franzes are over the edge, by usinghigher shuss modification on those franzes would create higher coverageon both bale sides.

1. A method of producing knitted netting, comprising: supplying lateralpolyolefin ribbons and longitudinal polyolefin ribbons to a knittingmachine; forming at least one modified lateral ribbon by passing saidlateral ribbons over a trick plate having at least one corrugated orcurved surface, said modified lateral ribbons having an actual ribbonlength that is at least 10% greater than a calculated ribbon lengthwhile knitting the lateral polyolefin ribbons with the longitudinalpolyolefin ribbons to form a knitted netting having at least onemodified lateral ribbon, wherein said netting exhibits reduced lateralshrinkage relative to netting produced with an actual ribbon lengthequal to said calculated ribbon length upon elongation up to 100%. 2.The method according to claim 1, comprising forming modified lateralpolyolefin ribbons along outside edges of said knitted netting.
 3. Themethod according to claim 1, wherein all of said lateral polyolefinribbons are formed to have an actual length that is at least 10% greaterthan said calculated ribbon length.
 4. The method according to claim 1,wherein said at least one modified lateral ribbon is formed to have anactual length that is at least 10%-30% greater than said calculatedribbon length.
 5. The method according to claim 3 wherein all of saidlateral polyolefin ribbons are formed to have an actual length that isat least 30% greater than said calculated ribbon length.
 6. The methodof claim 1, wherein the corrugated or curved surface is a separate pieceattached to the trick plate.
 7. A process of producing knitted nettingexhibiting reduced lateral shrinkage, comprising: feeding longitudinaland lateral polyolefin ribbons to a knitting machine, knitting saidlongitudinal polyolefin ribbons with at least one modified lateralpolyolefin ribbon in a knitting machine by forming at least one modifiedlateral ribbon by passing said lateral ribbons over a trick plate havingat least one corrugated or curved surface, said modified lateral ribbonshaving an actual ribbon length that is at least 10% greater than acalculated ribbon length to form a knitted netting which upon elongationup to 100% exhibits reduced lateral shrinkage relative to knittednetting produced with and actual ribbon length equal to said calculatedribbon length.
 8. The process according to claim 7, comprising knittingsaid longitudinal polyolefin ribbons with a plurality of modifiedlateral polyolefin ribbons.
 9. The process according to claim 7, whereinsaid lateral shrinkage is about 12% upon elongation of about 60%. 10.The process according to claim 8, wherein said lateral shrinkage isgreater than 0% lateral shrinkage and less than 10% upon elongation ofbetween about 20% and about 50%.
 11. The process according to claim 8,wherein said lateral shrinkage is between about 10% and about 20% uponelongation of between about 50% and about 70%.
 12. The process accordingto claim 8, wherein said lateral shrinkage is between about 20% to about30% upon elongation of between about 50% and about 80%.
 13. The processaccording to claim 8, wherein said lateral shrinkage is between about20% to about 50% upon elongation of between about 80% and 100%.
 14. Theprocess of claim 7, wherein the corrugated or curved surface is aseparate piece attached to the trick plate.
 15. A process of producingknitted netting exhibiting reduced lateral shrinkage, comprising:feeding longitudinal and lateral polyolefin ribbons to a knittingmachine, knitting said longitudinal polyolefin ribbons with at least onemodified lateral polyolefin ribbon in a knitting machine by forming atleast one modified lateral ribbon by passing said lateral ribbons over atrick plate having at least one corrugated or curved surface, saidmodified lateral ribbons having an actual ribbon length that is at least10%-30% greater than a calculated ribbon length to form a knittednetting which exhibits reduced lateral shrinkage upon elongation up to100% relative to knitted netting produced with and actual ribbon lengthequal to said calculated ribbon length.
 16. The process according toclaim 15, comprising knitting with a plurality of said modified lateralpolyolefin ribbons.
 17. The process according to claim 16, wherein saidlateral shrinkage is about 12% upon elongation of about 60%.
 18. Theprocess according to claim 16, wherein lateral shrinkage is greater than0% and less than 10% upon elongation of between about 20% and about 50%.19. The process according to claim 16, wherein said lateral shrinkage isbetween about 10% and about 20% upon elongation of between about 50% andabout 70%.
 20. The process according to claim 16, wherein said lateralshrinkage is between about 20% to about 30% upon elongation of betweenabout 50% and about 80%.
 21. The process according to claim 16, whereinsaid lateral shrinkage is between about 20% to about 50% upon elongationof between about 80% and about 100%.
 22. The process of claim 15,wherein the corrugated or curved surface is a separate piece attached tothe trick plate.
 23. A method of producing knitted netting, comprising:knitting polyolefin ribbons with a trick plate having at least oneoutwardly curved surface element to form knitted netting havinglongitudinal polyolefin ribbons and lateral polyolefin ribbons, whereinat least one of said lateral polyolefin ribbon is modified to have anactual length which is at least 10% greater than a calculated ribbonlength, to produce knitted netting which exhibits reduced lateralshrinkage upon elongation up to 100% relative to netting produced withan actual ribbon length equal to said calculated ribbon length.
 24. Theprocess according to claim 23, comprising knitting with a trick platehaving a plurality of outwardly curved surface elements.
 25. The processaccording to claim 23, wherein said lateral shrinkage is about 12% uponelongation of about 60%.
 26. The process according to claim 23, whereinlateral shrinkage is greater than 0% and less than 10% upon elongationof between about 20% and about 50%.
 27. The process according to claim23, wherein said lateral shrinkage is between about 10% and about 20%upon elongation of about 50% and about 70%.
 28. The process according toclaim 23, wherein said lateral shrinkage is between about 20% to about30% upon elongation between about 50% and about 80%.
 29. The processaccording to claim 23, wherein said lateral shrinkage 4 between about20% to about 50% upon elongation of between about 80% and about 100%.